The invention concerns the automatic activation of a fuse or ignition system serving to ignite fired projectiles, in particular spinning projectiles. The fuse includes at least two independent systems, one of which acts automatically when a predetermined number of revolutions is attained by the fired projectile.
The fuses of projectiles and their safety and activation systems usually must satisfy high requirements, in order to comply with the safety needs of the users. They must, above all, exhibit high mechanical strength to insure safety under all conceivable environmental conditions. This requires, among other requirements, that with regard to their structural layout, any defective assembly of the structural parts which would endanger safety, must be excluded. It further requires the faultless functioning of the activation systems during the assembly and the subsequent functional testing. Even though the above-mentioned absolute requirements demonstrate by themselves the care an ignition system requires, they are not satisfied by the structural design measures alone. Ignition systems must remain secured for a predetermined distance or during a predetermined time following the firing. During this period of time, the ignition system must not respond, for example, upon its impact against an obstacle or the receipt of an ignition signal.
Furthermore, the ignition system must not assume its activated state prior to attaining its activation time, upon the failure or loss of a structural part (group). To insure this, the system must contain two activating devices that are independent of each other and which require for their actuation environmental forces acting independently of each other. Complete activation therefore must be possible only as the result of firing (or its simulation).
The fact that relatively few of the known projectile fuse activation systems are satisfying these requirements is the result, among others, of the condition that it is difficult to install two systems acting independently of each other, in a relatively small structural space in the nose of the projectile. If, for example, electric or electronic systems are used, the size of the structural space available is of least importance, but in the case of such a system, the problem of the power supply must receive special attention. Even though entirely usable miniature batteries, button cells, etc., are available for this purpose, they have limited shelf life and applicability, not the least of which being the voltage drop taking place at low environmental temperatures. In view of this fact, attempting to maintain the power supply permanently in the ready condition in a peacetime, average-size stock of projectiles, would pose practically insoluble problems for ammunition depots and the like.
It is conventional to provide a vent in the fuse housing, which vent when exposed is operable to pass an ignition flash. Due to the drawbacks of electrical ignition systems, it is known to use a mechanical lever covering the vent and thus securing it, which lever exposing the vent under certain conditions.
Aside from the fact that the geometric and spatial conditions in the fuse of a projectile permit only a scant covering of the vent by the closing lever, the latter also has the disadvantage that it operates in a position-dependent manner. This means that it may expose the vent under certain conditions when not desired, for example when dropped, impacted or the like.
In view of this, it is the object of the invention to provide a structurally simple activation device, responsive to the rotational forces occurring upon the firing of the projectile, and only after a minimum rpm of the projectile has been attained. It should be understood that this device represents only one of the activating devices required in the fuse of the projectile.